A few coaches suggest squats every day, usually based on a 4, or even a 5 day, workout week. Most coaches want a form of regular squatting, a variety of squatting, each workout. One legged squats and step ups (not the same) can be included. Working one leg at a time can be important in sport training, ensuring an equal balance of strength in each leg. Not having a weaker leg than the other. Almost daily leg/squatting workouts are not meant for year round training. Probably 4 to 6 weeks and than back to a more normal protocol. A stronger muscle can be a faster muscle, improving the motor impulse/firing off/reaction abilities.Though in football, it may be a question of quickness, more than speed. But each can be improved through well planned workouts.
Some Olympic coaches (started with the former Eastern Block Olympic lifters & Russians) want at least 3 (sometimes more) squatting sessions per day. Lot of stories, and videos, about Bulgarian lifters (for example), coming off the street and without any warm up, squat (very deeply) 500-600 lbs for easy reps. All squatting workouts were brief and to the point. Few sets, few reps. And not going to failure at any time, to insure steady progress.
Overhead squats are an excellent form of squatting. Usually done from a deeper starting position. They do count as an excellent movement for thighs. As are squat cleans, another great leg movement. Good Luck.